In rotating filling machines for filling cans, the underside of a filler element has a discharge opening for the controlled discharge of the liquid product into the containers. It is usual to place a tulip there. The tulip is displaceable in the direction of the vertical filler element axis and has a container contact surface formed by at least one seal.
A tulip is moveable between a raised initial position, in which the container contact surface is situated at a spacing above the opening of each container located at the filler element, and a lowered position, in which, the container contact surface abuts in a sealed manner against the opening edge of the container surrounding the container opening.
A cam controls both this movement of the tulip between the raised and lowered positions, and the contact pressure of the tulip on the can. To implement this, each filler element has a control or lifting rod that is oriented with its longitudinal extension parallel to the filler element axis and that is guided at the filler element so as to be displaceable in this axis. The bottom end of the control or lifting rod connects to the tulip of the filler element.
A cam or control roller is mounted so as to be freely rotatable at the top end of the control or lifting rod. The cam or control roller interacts with a fixed control cam, i.e. not rotating with the rotor of the filling machine. The control or lifting rod is tensioned in a preliminary manner by spring means acting directly on the control or lifting rod and consequently the tulip is also tensioned in a preliminary manner into the raised position. Through the control cam interacting with the control roller, the control or lifting rod, and consequently also the tulip, is moved into the lowered position in opposition to the effect of the spring means.
One disadvantage, among others, is that the design of the filler elements is relatively complicated and time-consuming mechanically. The filler elements are therefore expensive and also subject to abrasive wear.
A further disadvantage is that the contact force with which the tulips of the filling machine abut against the respective container in the region of the container mouth are path-determined. The contact force can therefore change because of abrasive wear. In addition, the contact forces of different filler elements can be different from each other. This can result in a not inconsiderable impairment to the method of operation of a filling machine.
In known filling machines, it is not presently known how to regulate or adjust the contact pressure with which the tulips abut against the respective containers to be filled without spending non-justifiable amounts of money and time. It is also not known how to adapt the contact pressure to the fill pressure, which is dependent, among other things, on the liquid pressure and/or to the mechanical characteristics of the containers.